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summary
toSurface observations, soundings, and a thermodynamic budget are used to investigate the formation process of 93 arctic airmass events. The events involve very cold surface temperatures—an average of −42.8°C at Norman Wells (Tłegǫ́htı̨), a centrally located station in the formation region—and cooling in the 1000–500-hPa layer. A multistage process for their formation in northwestern Canada is proposed. This process is contrary to the classical conceptualization of extremely shallow, surface formations. In the first stage of formation, snow falls into a layer of unsaturated air in the lee of the Rocky Mountains, causing sublimational cooling and moistening the subcloud layer. Simultaneously, the midtroposphere is cooled by cloud-top radiation emissions. In the second stage, snowfall abates, the air column dries, and clear-sky surface radiational cooling predominates, augmented by the high emissivity of fresh snow cover. The surface temperature falls very rapidly, up to a maximum of 18°C day−1 in one event. In the final stage, after near-surface temperatures fall below the frost point, ice crystals and, nearer the surface, ice fog form. At the end of formation, there is cold-air damming, with a cold pool and anticyclone in the lee of the Rockies, lower pressure in the Gulf of Alaska, and an intense baroclinic zone oriented northwest to southeast along the mountains. There have been secular changes in the characteristics of the arctic air masses over the period 1948–2008. The surface temperature during the events has become warmer, and the air masses are deeper and moister. The 1000-hPa diabatic cooling during events, which includes latent heat and radiative processes, has decreased by 2.2°C day−1.
in The Development of Arctic Air Masses in Northwest Canada and Their Behavior in a Warming Climate
f | 1 | { | f | 1 | { |
2 | "Creator": "Jessica K. Turner and John R. Gyakum", | 2 | "Creator": "Jessica K. Turner and John R. Gyakum", | ||
3 | "author": null, | 3 | "author": null, | ||
4 | "author_email": null, | 4 | "author_email": null, | ||
5 | "creator_user_id": "80a5dcde-1c45-4f36-9a1d-46db676c889d", | 5 | "creator_user_id": "80a5dcde-1c45-4f36-9a1d-46db676c889d", | ||
6 | "description": "", | 6 | "description": "", | ||
7 | "funding_program": "", | 7 | "funding_program": "", | ||
8 | "geographic_range": [ | 8 | "geographic_range": [ | ||
9 | "NWT" | 9 | "NWT" | ||
10 | ], | 10 | ], | ||
11 | "groups": [], | 11 | "groups": [], | ||
12 | "id": "ff2aa240-0128-4da9-b623-61734a9e5e6d", | 12 | "id": "ff2aa240-0128-4da9-b623-61734a9e5e6d", | ||
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14 | "license_id": "notspecified", | 14 | "license_id": "notspecified", | ||
15 | "license_title": "License Not Specified", | 15 | "license_title": "License Not Specified", | ||
16 | "local_relevance": "The study is highly relevant to northwestern | 16 | "local_relevance": "The study is highly relevant to northwestern | ||
17 | Canada as it investigates the formation of extremely cold Arctic air | 17 | Canada as it investigates the formation of extremely cold Arctic air | ||
18 | masses specifically in this region. These cold air masses impact the | 18 | masses specifically in this region. These cold air masses impact the | ||
19 | local climate, particularly during winter, affecting communities, | 19 | local climate, particularly during winter, affecting communities, | ||
20 | infrastructure, and ecosystems. Understanding the formation process, | 20 | infrastructure, and ecosystems. Understanding the formation process, | ||
21 | especially given the unique three-stage mechanism identified in the | 21 | especially given the unique three-stage mechanism identified in the | ||
22 | study, is essential for predicting and preparing for extreme cold | 22 | study, is essential for predicting and preparing for extreme cold | ||
23 | events in northwestern Canada. Additionally, the finding of a warming | 23 | events in northwestern Canada. Additionally, the finding of a warming | ||
24 | trend and changes in the characteristics of these air masses over | 24 | trend and changes in the characteristics of these air masses over | ||
25 | recent decades highlights potential climate change impacts in this | 25 | recent decades highlights potential climate change impacts in this | ||
26 | area, which can inform long-term planning and climate adaptation | 26 | area, which can inform long-term planning and climate adaptation | ||
27 | strategies for northern Canadian regions.", | 27 | strategies for northern Canadian regions.", | ||
28 | "maintainer": null, | 28 | "maintainer": null, | ||
29 | "maintainer_email": null, | 29 | "maintainer_email": null, | ||
30 | "metadata_created": "2024-11-10T23:38:01.608665", | 30 | "metadata_created": "2024-11-10T23:38:01.608665", | ||
n | 31 | "metadata_modified": "2024-11-10T23:47:25.377257", | n | 31 | "metadata_modified": "2025-04-25T14:05:29.342987", |
32 | "metatags": "Arctic,Synoptic-scale processes,Norman Wells", | 32 | "metatags": "Arctic,Synoptic-scale processes,Norman Wells", | ||
33 | "modified_date": "2011-09-01", | 33 | "modified_date": "2011-09-01", | ||
34 | "name": | 34 | "name": | ||
35 | r-masses-in-northwest-canada-and-their-behavior-in-a-warming-climate", | 35 | r-masses-in-northwest-canada-and-their-behavior-in-a-warming-climate", | ||
36 | "notes": "This study examines the formation of 93 Arctic airmass | 36 | "notes": "This study examines the formation of 93 Arctic airmass | ||
37 | events in northwestern Canada, and propose a novel three-stages | 37 | events in northwestern Canada, and propose a novel three-stages | ||
38 | mechanism of extremely shallow, surface formations. ", | 38 | mechanism of extremely shallow, surface formations. ", | ||
39 | "num_resources": 1, | 39 | "num_resources": 1, | ||
40 | "num_tags": 3, | 40 | "num_tags": 3, | ||
41 | "organization": { | 41 | "organization": { | ||
42 | "approval_status": "approved", | 42 | "approval_status": "approved", | ||
43 | "created": "2023-11-30T14:30:44.490751", | 43 | "created": "2023-11-30T14:30:44.490751", | ||
44 | "description": "The AMS is a global community committed to | 44 | "description": "The AMS is a global community committed to | ||
45 | advancing weather, water, and climate science and service.", | 45 | advancing weather, water, and climate science and service.", | ||
46 | "id": "d4b3fa25-b87c-4bc3-9bca-83ad827f9f2e", | 46 | "id": "d4b3fa25-b87c-4bc3-9bca-83ad827f9f2e", | ||
47 | "image_url": "2024-01-22-171329.375793download.jfif", | 47 | "image_url": "2024-01-22-171329.375793download.jfif", | ||
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49 | "name": "american-meteorological-society", | 49 | "name": "american-meteorological-society", | ||
50 | "state": "active", | 50 | "state": "active", | ||
51 | "title": "American Meteorological Society", | 51 | "title": "American Meteorological Society", | ||
52 | "type": "organization" | 52 | "type": "organization" | ||
53 | }, | 53 | }, | ||
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58 | "release_date": "2011-09-01", | 58 | "release_date": "2011-09-01", | ||
59 | "resources": [ | 59 | "resources": [ | ||
60 | { | 60 | { | ||
61 | "cache_last_updated": null, | 61 | "cache_last_updated": null, | ||
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63 | "created": "2024-11-10T23:38:26.152364", | 63 | "created": "2024-11-10T23:38:26.152364", | ||
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72 | "mimetype": "application/pdf", | 72 | "mimetype": "application/pdf", | ||
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74 | "name": "The Development of Arctic Air Masses in Northwest | 74 | "name": "The Development of Arctic Air Masses in Northwest | ||
75 | Canada and Their Behavior in a Warming Climate", | 75 | Canada and Their Behavior in a Warming Climate", | ||
76 | "package_id": "ff2aa240-0128-4da9-b623-61734a9e5e6d", | 76 | "package_id": "ff2aa240-0128-4da9-b623-61734a9e5e6d", | ||
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85 | ], | 85 | ], | ||
86 | "state": "active", | 86 | "state": "active", | ||
87 | "summary": "Surface observations, soundings, and a thermodynamic | 87 | "summary": "Surface observations, soundings, and a thermodynamic | ||
88 | budget are used to investigate the formation process of 93 arctic | 88 | budget are used to investigate the formation process of 93 arctic | ||
89 | airmass events. The events involve very cold surface | 89 | airmass events. The events involve very cold surface | ||
t | 90 | temperatures\u2014an average of \u221242.8\u00b0C at Norman Wells, a | t | 90 | temperatures\u2014an average of \u221242.8\u00b0C at Norman Wells |
91 | centrally located station in the formation region\u2014and cooling in | 91 | (T\u0142ego\u0328\u0301ht\u0131\u0328), a centrally located station in | ||
92 | the 1000\u2013500-hPa layer. A multistage process for their formation | 92 | the formation region\u2014and cooling in the 1000\u2013500-hPa layer. | ||
93 | in northwestern Canada is proposed. This process is contrary to the | 93 | A multistage process for their formation in northwestern Canada is | ||
94 | classical conceptualization of extremely shallow, surface | 94 | proposed. This process is contrary to the classical conceptualization | ||
95 | formations.\r\n\r\nIn the first stage of formation, snow falls into a | 95 | of extremely shallow, surface formations.\r\n\r\nIn the first stage of | ||
96 | layer of unsaturated air in the lee of the Rocky Mountains, causing | 96 | formation, snow falls into a layer of unsaturated air in the lee of | ||
97 | sublimational cooling and moistening the subcloud layer. | 97 | the Rocky Mountains, causing sublimational cooling and moistening the | ||
98 | Simultaneously, the midtroposphere is cooled by cloud-top radiation | 98 | subcloud layer. Simultaneously, the midtroposphere is cooled by | ||
99 | emissions. In the second stage, snowfall abates, the air column dries, | 99 | cloud-top radiation emissions. In the second stage, snowfall abates, | ||
100 | and clear-sky surface radiational cooling predominates, augmented by | 100 | the air column dries, and clear-sky surface radiational cooling | ||
101 | the high emissivity of fresh snow cover. The surface temperature falls | 101 | predominates, augmented by the high emissivity of fresh snow cover. | ||
102 | very rapidly, up to a maximum of 18\u00b0C day\u22121 in one event. In | 102 | The surface temperature falls very rapidly, up to a maximum of | ||
103 | the final stage, after near-surface temperatures fall below the frost | 103 | 18\u00b0C day\u22121 in one event. In the final stage, after | ||
104 | point, ice crystals and, nearer the surface, ice fog form. At the end | 104 | near-surface temperatures fall below the frost point, ice crystals | ||
105 | of formation, there is cold-air damming, with a cold pool and | 105 | and, nearer the surface, ice fog form. At the end of formation, there | ||
106 | anticyclone in the lee of the Rockies, lower pressure in the Gulf of | 106 | is cold-air damming, with a cold pool and anticyclone in the lee of | ||
107 | Alaska, and an intense baroclinic zone oriented northwest to southeast | 107 | the Rockies, lower pressure in the Gulf of Alaska, and an intense | ||
108 | baroclinic zone oriented northwest to southeast along the | ||||
108 | along the mountains.\r\n\r\nThere have been secular changes in the | 109 | mountains.\r\n\r\nThere have been secular changes in the | ||
109 | characteristics of the arctic air masses over the period | 110 | characteristics of the arctic air masses over the period | ||
110 | 1948\u20132008. The surface temperature during the events has become | 111 | 1948\u20132008. The surface temperature during the events has become | ||
111 | warmer, and the air masses are deeper and moister. The 1000-hPa | 112 | warmer, and the air masses are deeper and moister. The 1000-hPa | ||
112 | diabatic cooling during events, which includes latent heat and | 113 | diabatic cooling during events, which includes latent heat and | ||
113 | radiative processes, has decreased by 2.2\u00b0C day\u22121.", | 114 | radiative processes, has decreased by 2.2\u00b0C day\u22121.", | ||
114 | "tags": [ | 115 | "tags": [ | ||
115 | { | 116 | { | ||
116 | "display_name": "Arctic", | 117 | "display_name": "Arctic", | ||
117 | "id": "25dee16e-a24a-4238-a428-3617178f21cc", | 118 | "id": "25dee16e-a24a-4238-a428-3617178f21cc", | ||
118 | "name": "Arctic", | 119 | "name": "Arctic", | ||
119 | "state": "active", | 120 | "state": "active", | ||
120 | "vocabulary_id": null | 121 | "vocabulary_id": null | ||
121 | }, | 122 | }, | ||
122 | { | 123 | { | ||
123 | "display_name": "Norman Wells", | 124 | "display_name": "Norman Wells", | ||
124 | "id": "e41f9418-b86a-45aa-85ea-cfdcc609fd47", | 125 | "id": "e41f9418-b86a-45aa-85ea-cfdcc609fd47", | ||
125 | "name": "Norman Wells", | 126 | "name": "Norman Wells", | ||
126 | "state": "active", | 127 | "state": "active", | ||
127 | "vocabulary_id": null | 128 | "vocabulary_id": null | ||
128 | }, | 129 | }, | ||
129 | { | 130 | { | ||
130 | "display_name": "Synoptic-scale processes", | 131 | "display_name": "Synoptic-scale processes", | ||
131 | "id": "53a9ff97-dc86-45b4-8b19-13f72a57c2e2", | 132 | "id": "53a9ff97-dc86-45b4-8b19-13f72a57c2e2", | ||
132 | "name": "Synoptic-scale processes", | 133 | "name": "Synoptic-scale processes", | ||
133 | "state": "active", | 134 | "state": "active", | ||
134 | "vocabulary_id": null | 135 | "vocabulary_id": null | ||
135 | } | 136 | } | ||
136 | ], | 137 | ], | ||
137 | "title": "The Development of Arctic Air Masses in Northwest Canada | 138 | "title": "The Development of Arctic Air Masses in Northwest Canada | ||
138 | and Their Behavior in a Warming Climate", | 139 | and Their Behavior in a Warming Climate", | ||
139 | "type": "dataset", | 140 | "type": "dataset", | ||
140 | "url": null, | 141 | "url": null, | ||
141 | "version": null | 142 | "version": null | ||
142 | } | 143 | } |